The invention relates to internal combustion engines for marine propulsion devices, and, more particularly, to crankshaft bearing arrangements for such internal combustion engines.
In the marine art, it is common to attach the flywheel hub to the upper end of the crankshaft at a point above the upper main crankshaft bearing and seal. Therefore, the portion of the crankshaft extending upwardly from the engine block is necessarily as long as the combined lengths of the upper main bearing, the seal, and the flywheel hub.
Also, at a certain rpm which varies depending on engine construction, a flywheel undergoes a phenomenon known as second order reverse whirl, i.e., the flywheel "wobbles" in the direction opposite the direction of flywheel rotation.
Attention is directed to the following U.S. patents:
______________________________________ Matsumoto 4,452,195 June 5, 1984 Honda 4,262,552 April 21, 1981 Katsumata 4,146,806 March 27, 1979 Farr 4,095,922 June 20, 1978 Carlsson 3,955,550 May 11, 1976 ______________________________________